In many fields of technology, it is desirable to use robots with an autonomous behaviour such that they freely can move around a space without colliding with possible obstacles.
Robotic vacuum cleaners are know in the art, which are equipped with drive means in the form of a motor for moving the cleaner across a surface to be cleaned. The robotic vacuum cleaners are further equipped with intelligence in the form of microprocessor(s) and navigation means for causing an autonomous behaviour such that the robotic vacuum cleaners freely can move around and clean a space in the form of e.g. a room. Thus, these prior art robotic vacuum cleaners has the capability of more or less autonomously vacuum cleaning a room in which furniture such as tables and chairs and other obstacles such as walls and stairs are located. Traditionally, these robotic vacuum cleaners have navigated a room by means of using e.g. ultrasound or light waves. Further, the robotic vacuum cleaners typically must be complemented with additional sensors, such as stair sensors, wall-tracking sensors and various transponders to perform accurately.
A large number of prior art robot vacuum cleaners use a technology referred to as Simultaneous Localization and Mapping (SLAM). SLAM is concerned with the problem of building a map of an unknown environment by a mobile robot while at the same time navigating the environment using the map. This is typically combined with a horizontally scanning laser for range measurement. Further, odometry is used to provide an approximate position of the robot as measured by the movement of the wheels of the robot.
US 2002/0091466 discloses a mobile robot with a first camera directed toward the ceiling of a room for recognizing a base mark on the ceiling and a line laser for emitting a linear light beam toward an obstacle, a second camera for recognizing a reflective linear light beam from the obstacle. The line laser emits a beam in the form of straight line extending horizontally in front of the mobile robot.
Further methods known in the art comprise horizontal laser scanning of an area to be represented in 3D, in combination with a camera recording images the area. Features can thus be extracted from the recorded images in order to create the 3D representation.
The process of causing robotic cleaning devices to behave in an autonomous manner is highly complex, even when the robotic cleaning device navigates over a plane surface, and becomes even more complex when the robotic cleaning device is to consider objects and further transverse these objects such as for instance doorsteps.